JP7624374B2 - Stage device and charged particle beam device equipped with stage device - Google Patents

Description

The present invention relates to a stage device and a charged particle beam device equipped with a stage device.

In the semiconductor-related field, stage devices are known for moving and accurately positioning samples such as semiconductor wafers. In addition, in devices that handle charged particle beams such as electron beams, samples such as semiconductor wafers must be handled in a high vacuum environment, and the stage devices also operate in a high vacuum environment.

The structure of the stage device is classified into a guide rail type stage, which is limited to movement only along the guide rail and mechanically prohibited from moving in other directions, and a floating type stage, which floats from the base and moves under control without contacting the base. In order to realize planar movement in a guide rail type stage, a two-stage structure is used in which the upper stage moves in a direction perpendicular to the direction of movement of the lower stage. On the other hand, floating type stages include a single-axis operation type that has a large range of movement only in one direction and a narrow range of movement in other directions, and a planar operation type that can move widely in a plane. It is also possible to configure a stage that moves in a plane by combining a single-axis operation type floating type stage with a guide rail type stage. Furthermore, the floating mechanism of a floating type stage includes a magnetic floating type that uses electromagnetic force to control the amount of floating, and an air bearing type that uses gas pressure to control the amount of floating.

Magnetically levitated stages are further classified into two types: one with an electromagnet that gives the stage buoyancy and a linear motor that gives thrust in one axis direction, and one with a shaft motor that can perform both levitation and propulsion functions in one. Both types allow the stage to move while maintaining a non-contact state. The non-contact state means that no mechanical stabilization mechanism can be obtained, but advanced control of the levitated stage may enable high positional accuracy of the stage.

When a floating stage is placed in a vacuum environment, the heat generated by the motor that drives the stage cannot be dissipated by solid thermal conduction, so a heat dissipation means using a refrigerant is required. For example, Patent Document 1 discloses a technology for cooling the drive unit inside the fine movement stage that moves the wafer with a refrigerant. Patent Document 2 discloses a technology for cooling the motor coil with a refrigerant in a stage device that uses a shaft-type motor to move a substrate table on which a wafer is placed. Furthermore, Patent Document 3 discloses a technology related to a cooling device that cools a linear motor that moves a wafer stage on which a wafer is placed.

JP 2005-32817 A JP 2001-61269 A JP 2005-64229 A

In the manufacturing, measurement, and inspection processes of semiconductor wafers, the wafer must be positioned accurately. In order to accurately position the semiconductor wafer, the position of the stage on which the wafer is moved must be accurately known. One technology for accurately measuring the position of the stage is to use a laser interferometer-type distance measurement device, which installs a mirror bar on the stage, shines laser light on its reflective surface, and uses the interference between the incident light and the reflected light to measure distance. Recent laser interferometer-type distance measurement devices are capable of measuring distance with an accuracy on the order of picometers. If distance measurements could be performed with an accuracy of that order, it would seem that sufficient wafer position accuracy could be obtained for practical purposes. However, in reality, in floating stages, various error factors that deteriorate the wafer position accuracy are combined, making it difficult to ensure sufficient wafer position accuracy.

Therefore, the present invention provides a technology that ensures sufficient positional accuracy of the sample on a floating stage.

The stage device of the present invention includes a first stage that moves in a first direction, a second stage that rises from the first stage and moves in a second direction perpendicular to at least the first direction, a first cooling unit that cools the table of the first stage with a refrigerant, and a control device that controls the inclination of the second stage based on the table of the first stage cooled by the first cooling unit.

The present invention makes it possible to ensure sufficient positional accuracy of the sample on the floating stage.

1 is a diagram showing an overall configuration of a stage device according to a first embodiment. 1 is a cross-sectional view of a stage device according to a first embodiment. FIG. 2 is a diagram showing a control device of the stage apparatus according to the first embodiment. FIG. 13 is a diagram showing the overall configuration of a stage device according to a second embodiment. FIG. 13 is a diagram showing the overall configuration of a charged particle beam device according to a third embodiment.

The embodiments of the present invention will be described in detail with reference to the drawings. It goes without saying that in the following embodiments, the components (including element steps, etc.) are not necessarily essential unless specifically stated otherwise or considered to be obviously essential in principle.

Example 1
FIG. 1 is a diagram showing the overall configuration of a stage device of the first embodiment. FIG. 2 is a cross-sectional view of the stage device of the first embodiment. The stage device 100 of the first embodiment is a device that moves a placed sample (e.g., a semiconductor wafer) in the X-axis direction and the Y-axis direction. The stage device 100 includes an upper stage 10 that moves in the X-axis direction, a lower stage 20 that moves in the Y-axis direction, a cooling water pipe 30 that supplies cooling water for cooling the upper stage 10 and the lower stage 20, and a control device 50 (see FIG. 3). The upper stage 10 floats from the lower stage 20 by the magnetic force between the upper stage 10 and the lower stage 20, and moves at least in the X-axis direction perpendicular to the Y-axis direction.

(Upper stage 10)
The upper stage 10 is configured with the X-table 1 at its center. The upper stage 10 floats from the Y-table 2 of the lower stage 20 and moves in the X-axis direction relative to the lower stage 20. The upper stage 10 mainly moves in the X-axis direction, but the direction of movement includes a deviation from the X-axis direction by an amount equivalent to an error. The upper stage 10 may move not only in the X-axis direction but also in a plane. Various mechanisms are attached to the upper stage 10, such as a mechanism for floating the upper stage 10 from the Y-table 2, a mechanism for moving the upper stage 10 in the X-axis direction, and a mechanism for moving the upper stage 10 in the Y-axis direction. These various mechanisms are provided inside the X-table 1. These various mechanisms become heat sources and conduct heat to the X-table 1.

On the X table 1, the X mirror 3, which is a mirror bar for measuring the X coordinate, and the Y mirror 4, which is a mirror bar for measuring the Y coordinate, are fixed. The X mirror 3 has a reflecting surface perpendicular to the X axis, and reflects the laser light emitted from a laser interferometer type distance measuring device (not shown). The Y mirror 4 has a reflecting surface perpendicular to the Y axis, and reflects the laser light emitted from a laser interferometer type distance measuring device (not shown). This makes it possible to measure the X coordinate of the reflecting surface of the X mirror 3 and the Y coordinate of the reflecting surface of the Y mirror 4. By measuring the X and Y coordinates of the reflecting surfaces, the X and Y coordinates of the X table 1 to which the X mirror 3 and Y mirror 4 are fixed and the X and Y coordinates of the sample placed on the X table 1 are calculated.

(Lower stage 20)
The lower stage 20 is configured with the Y table 2 at its center. The lower stage 20 moves in the Y-axis direction. The lower stage 20 mainly moves in the Y-axis direction, but the direction of movement includes a deviation of an error level with respect to the Y-axis direction. The lower stage 20 may move not only in the Y-axis direction but also in a plane. The lower stage 20 moves in the Y-axis direction on two guide rails 5 arranged along the Y-axis direction. The lower stage 20 is restrained by the two guide rails 5 so that it cannot move in any direction other than the Y-axis direction. The lower stage 20 in the first embodiment is a guide rail type, but it may be a floating type stage. The lower stage 20 has various mechanisms, such as a mechanism for floating the upper stage 10 from the Y table 2 and a mechanism for moving the lower stage 20 in the Y-axis direction. These various mechanisms are provided inside the Y table 2. These various mechanisms become heat sources and conduct heat to the Y table 2.

(Cooling water piping 30)
The stage device 100 may be used in a sample chamber in which a sample such as a semiconductor wafer is manufactured, measured, or inspected. In addition, in an apparatus that handles a charged particle beam such as an electron beam, the sample such as a semiconductor wafer must be handled in a high vacuum environment, and the stage device 100 also operates in a high vacuum environment. In order to suppress malfunctions and thermal expansion caused by heat generated by the mechanism that moves the upper stage 10 and the lower stage 20, it is necessary to cool the upper stage 10 and the lower stage 20. In the first embodiment, the stage device 100 includes a cooling water pipe 30 that supplies a coolant to the upper stage 10 and the lower stage 20 in order to cool the upper stage 10 and the lower stage 20. In the first embodiment, cooling water is used as the coolant. As a cooling method for the stage device 100, water cooling, air cooling, gas cooling, and the like can be adopted.

Cooling water supplied from a constant temperature water tank (not shown) is supplied to both the upper stage 10 and the lower stage 20 through the cooling water pipe 30. The cooling water pipe 30 has a joint 31, a forward pipe 32, a crossover pipe 33, a return pipe 34, and a joint 35. The constant temperature water tank supplies cooling water to the forward pipe 32 connected to the joint 31. The forward pipe 32 is connected to a heat exchanger 17 (see FIG. 2) provided inside the X table 1 of the upper stage 10. The forward pipe 32 is arranged along the Y axis direction from the joint 31, turns in a U-shape, and then is arranged along the Y axis direction. The forward pipe 32 arranged along the Y axis direction is supported by a support 21 provided on the lower stage 20. In this way, by turning the forward pipe 32 into a U-shape, the part where it turns in a U-shape is displaced in accordance with the movement of the lower stage 20 in the Y axis direction. For this reason, the cooling water pipes 30 are made of a material that can be flexibly bent, such as a resin tube.

The forward pipe 32 that has passed the support 21 is arranged along the X-axis direction, turns in a U-shape, and then is arranged along the X-axis direction. The forward pipe 32 arranged along the X-axis direction is supported by the support 11 provided on the upper stage 10. In this way, by turning the forward pipe 32 into a U-shape, the part where it turns into a U-shape is displaced in accordance with the movement of the upper stage 10 in the X-axis direction. The forward pipe 32 that has passed the support 11 is connected to the joint 12 fixed to the X-table 1. As a result, the cooling water supplied from the constant temperature water tank is supplied to the heat exchanger 17 of the X-table 1 via the joint 31, the forward pipe 32, and the joint 12. As a result, the X-table 1 that comes into contact with the surface of the heat exchanger 17 through which the cooling water passes is cooled.

The cooling water used to cool the X table 1 is supplied to the heat exchanger 27 of the Y table 2 from the joint 13 fixed to the X table 1 via the crossover pipe 33. The crossover pipe 33 is supported by the support 11. The crossover pipe 33 supported by the support 11 is arranged along the X axis direction, turns into a U shape, and then arranged along the X axis direction. The crossover pipe 33 is then connected to the joint 22 fixed to the Y table 2. As a result, the cooling water used to cool the X table 1 is supplied to the heat exchanger 27 of the Y table 2 via the joint 13, the crossover pipe 33, and the joint 22. As a result, the Y table 2, which is in contact with the surface of the heat exchanger 27 through which the cooling water passes, is cooled.

The cooling water used to cool the Y table 2 returns to the constant temperature water tank from the joint 23 fixed to the Y table 2 via the return pipe 34. The return pipe 34 is supported by the support 21. The return pipe 34 supported by the support 21 is arranged along the Y axis direction, turns into a U shape, and then arranged along the Y axis direction. The return pipe 34 is then connected to a joint 35 of the constant temperature water tank. The cooling water cooled in the constant temperature water tank is supplied again to the joint 31.

The forward pipe 32 and the crossover pipe 33 are connected to a surface 16 perpendicular to the Y-axis direction of the upper stage 10. The crossover pipe 33 and the return pipe 34 are connected to a surface 28 perpendicular to the Y-axis direction of the lower stage 20. The vertical surface 16 of the upper stage 10 to which the forward pipe 32 and the crossover pipe 33 are connected and the vertical surface 28 of the lower stage 20 to which the crossover pipe 33 and the return pipe 34 are connected are on the same side. The vertical surface 16 of the upper stage 10 to which the forward pipe 32 and the crossover pipe 33 are connected and the vertical surface 28 of the lower stage 20 to which the crossover pipe 33 and the return pipe 34 are connected may be on different sides. For example, the forward pipe 32 and the crossover pipe 33 may be connected to a surface 18 perpendicular to the X-axis direction of the upper stage 10, and the crossover pipe 33 and the return pipe 34 may be connected to a surface 28 perpendicular to the Y-axis direction of the lower stage 20.

(Tilt angle of upper stage 10)
The control device 50 measures the inclination angle of the upper stage 10 and controls the upper stage 10 so that it is horizontal. The Y table 2 has a vertical surface 24 perpendicular to the Y axis direction, and a linear scale 25 (see FIG. 3) is attached to the vertical surface 24. The X table 1 has a vertical surface 14 perpendicular to the Y axis direction, and a sensor 15 (see FIG. 3) for reading the linear scale 25 is attached to the vertical surface 14. The vertical surfaces 24 and 14 face each other. When the linear scale 25 is read by the sensor 15, it becomes possible to measure the height of the X table 1 relative to the Y table 2 (Z displacement measurement). The linear scale 25 is, for example, a plate-like object having a pattern formed of a fine lattice that reflects laser light, and is used in combination with the sensor 15 that emits laser light and reads the reflected light. If the reflection pattern formed on the linear scale 25 is two-dimensional, it becomes possible to measure not only the amount of displacement of the relative positions of the linear scale 25 and the sensor 15 in the Z axis direction, but also the amount of displacement in the X axis direction. Furthermore, if height measurements are performed with two sensors on one linear scale, the tilt angle of the X-table 1 can be obtained from the difference in height between the two points. In other words, it becomes possible to measure the pitch angle of the X-table 1 moving in the X-axis direction. Using this principle, if two more sets of linear scales 25 and sensors 15 are added, it becomes possible to measure the yawing angle and the rolling angle. As a result, it becomes possible to perform highly accurate tilt angle measurements with a simple configuration.

(Heat exchanger)
FIG. 2 is a cross-sectional view taken along the line S1-S2 in FIG. 1. With reference to FIG. 2, a structure for cooling the X-table 1 and the Y-table 2 will be specifically described. The X-table 1 is made of an aluminum alloy. The X-table 1 has a heat exchanger 17 formed of stainless steel piping inside. This heat exchanger 17 is a cooling unit that cools the X-table 1 with a refrigerant. The heat exchanger 17 built into the X-table 1 cools the X-table 1 by contacting the surface of the piping through which the refrigerant (for example, cooling water) passes with the X-table 1. The piping constituting the heat exchanger 17 is formed by bending a single pipe, and the single pipe has an inlet and outlet for the cooling water. The X-table 1 is equipped with a mechanism for lifting the upper stage 10 from the Y-table 2, a mechanism for moving the upper stage 10 in the X-axis direction, a mechanism for moving the upper stage 10 in the Y-axis direction, and the like. These mechanisms become heat sources and conduct heat to the X-table 1. Since the X-table 1 is made of an aluminum alloy, the temperature gradient caused by heat conduction is small, making it possible to reduce temperature rise and temperature unevenness.

Similarly, the Y table 2 is also made of an aluminum alloy. The Y table 2 also has a heat exchanger 27 made of stainless steel piping inside. This heat exchanger 27 is a cooling unit that cools the Y table 2 with a refrigerant. The heat exchanger 27 built into the Y table 2 cools the Y table 2 by contacting the surface of the piping through which the refrigerant passes with the Y table 2. The piping that constitutes the heat exchanger 27 is also formed by bending a single pipe, and the single pipe has an inlet and outlet for cooling water. The Y table 2 is equipped with a mechanism for lifting the upper stage 10 from the Y table 2, a mechanism for moving the lower stage 20 in the Y-axis direction, and the like. The mechanism serves as a heat source and conducts heat to the Y table 2. Since the Y table 2 is also made of an aluminum alloy, the temperature gradient associated with heat conduction is small, making it possible to reduce temperature rise and temperature unevenness.

(Guide rail 5 and slide unit 26)
The lower stage 20, which is centered on the Y table 2, is restrained by two guide rails 5 so that it cannot move in any direction other than the Y-axis direction. The guide rails 5 are fixed to the sample chamber 40. The lower stage 20 has slide units 26 arranged at the four corners of the lower stage 20, and the slide units 26 come into contact with the guide rails 5. A rolling body is arranged inside the slide unit 26, and this rolling body makes rolling contact with the guide rails 5. As a result, the slide unit 26 and the guide rails 5 form a contact structure that is low friction but has no play.

When the temperature of the Y table 2 rises, the movement of the Y table 2 in the Y-axis direction is not restricted, so the Y table 2 expands freely in the Y-axis direction. On the other hand, the movement in directions other than the Y-axis direction is restricted by the guide rail 5, so the Y table 2 cannot expand in any direction other than the Y-axis direction. For this reason, the expansion due to the temperature rise is absorbed by the Y table 2 curving in a mountain shape. In other words, when the Y table 2 curves in a mountain shape, the Y table 2 slopes downward to the right on the right side of FIG. 2, and the Y table 2 slopes downward to the left on the left side of FIG. 2. On the other hand, the X table 1 moves to the positive or negative side of the X coordinate. Then, when the X table 1 moves, the inclination angle of the X table 1 is measured at the location where it has moved to, with the Y table 2 as the reference.

(Control device 50)
The control device 50 controls the stage driving mechanism 60 to move the lower stage 20 in the Y-axis direction, move the upper stage 10 in the Y-axis and X-axis directions, and change the inclination of the upper stage 10. The stage driving mechanism 60 includes a mechanism for lifting the upper stage 10 from the Y table 2, a mechanism for moving the upper stage 10 in the X-axis direction, a mechanism for moving the upper stage 10 in the Y-axis direction, and a mechanism for moving the lower stage 20 in the Y-axis direction. The control device 50 of the first embodiment measures the inclination angle of the X table 1, and controls the inclination of the X table 1 based on the measured inclination angle so that the X table 1 is horizontal.

The control device 50 controls the inclination of the upper stage 10 based on the Y table 2 of the lower stage 20, which is cooled by the heat exchanger 27. Specifically, the control device 50 measures the position of the upper stage 10 at multiple points based on the vertical surface 24 provided on the Y table 2, and controls the inclination of the upper stage 10 based on the measurement results.

The control device 50 also measures the XY coordinates of the X table 1 of the upper stage 10 based on the laser light reflected by the X mirror 3 and the Y mirror 4. The control device 50 then controls the movement of the upper stage 10 and the lower stage 20 based on the XY coordinates of the X table 1, and moves the sample placed on the upper stage 10 to the desired position.

Next, the hardware configuration of the control device 50 will be described with reference to FIG. 3. The control device 50 has a processor 51, a communication interface 52 (hereinafter, interface will be abbreviated as I/F), a main memory device 53, an auxiliary memory device 54, an input/output I/F 55, and a bus 56 that connects the above-mentioned modules so that they can communicate with each other.

The processor 51 is a central processing unit that controls the operation of each part of the stage device 100. The processor 51 is, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an ASIC (Application Specific Integrated Circuit). The processor 51 deploys the programs stored in the auxiliary storage device 54 in an executable manner in the working area of the main storage device 53. The main storage device 53 stores the programs executed by the processor 51, the data processed by the processor, and the like. The main storage device 53 is, for example, a flash memory, a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The auxiliary storage device 54 stores various programs and various data. The auxiliary storage device 54 stores, for example, an OS (Operating System), various programs, various tables, and the like. The auxiliary storage device 54 is, for example, a silicon disk including a non-volatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)), a solid state drive device, a hard disk (HDD, Hard Disk Drive) device, and the like.

The communication I/F 52 is an interface for connecting the stage device 100 to the outside via a network so that the device can communicate with the outside. The input/output I/F 55 receives the measurement results of the sensor 15 and the distance measurement device 70 connected to the input/output I/F 55. The distance measurement device 70 is a laser interferometer type distance measurement device that irradiates the reflecting surfaces of the X mirror 3 and the Y mirror 4 with laser light. The processor 51 calculates the tilt angle of the X table 1 based on the measurement results of the sensor 15, and controls the stage drive mechanism 60 so that the X table 1 is horizontal based on the calculated tilt angle of the X table 1. The processor 51 also measures the XY coordinates of the X table 1 and the XY coordinates of the sample placed on the X table 1 based on the measurement results of the distance measurement device 70. The input/output I/F 55 also outputs a drive command to the stage drive mechanism 60 connected to the input/output I/F 55. The stage driving mechanism 60 moves the lower stage 20 in the Y-axis direction, moves the upper stage 10 in the Y-axis and X-axis directions, and changes the tilt angle of the upper stage 10 in accordance with driving instructions from the control device 50.

(Effects of Example 1)
The control device 50 controls the inclination of the upper stage 10 with reference to the Y table 2 cooled by the heat exchanger 27, thereby enabling the upper stage 10 to be kept horizontal with high precision. In the first embodiment, the movement of the Y table 2 in directions other than the Y-axis direction is restricted by the guide rail 5, so that if the Y table 2 is not cooled, the Y table 2 will expand thermally and bend into a mountain shape. Even if the X table 1 is controlled to be horizontal with reference to the Y table 2, the X table 1 will not actually be horizontal due to the curvature of the Y table 2, which is the reference for calculating the inclination angle of the X table 1. Therefore, in the first embodiment, the curvature of the Y table 2, which is the reference, is suppressed by cooling the Y table 2, and it becomes possible to control the X table 1 to be horizontal with high precision. This makes it possible to precisely keep the XY plane, which is the XY coordinates of the sample, parallel to the horizontal plane of the upper stage 10. If the height of the plane for measuring the position coordinates of the upper stage 10 and the plane for the position coordinates of the sample coincide with each other, even if there is a slight angle deviation between the two, the error in the coordinates will be small. However, if there is a difference in height between the two, a coordinate error occurs that is proportional to the product of the height difference and the angle difference. In the first embodiment, by accurately aligning the upper stage 10 horizontally, the angle difference is reduced, and the above-mentioned coordinate error is reduced, thereby improving the positioning accuracy of the sample.

In addition, in the first embodiment, the cooling water used to cool the X table 1 on the upper stage 10 is used to cool the Y table 2 on the lower stage 20, so that the two tables can be cooled with the same cooling water.

In addition, in Example 1, the upper stage 10 is levitated from the lower stage 20 by magnetic force, which prevents the effects of thermal expansion of the lower stage 20 from being directly transmitted to the upper stage 10.

In addition, in Example 1, the tilt of the upper stage 10 can be calculated with a simple configuration by measuring the position of the upper stage 10 at multiple points based on the vertical surface 24 provided on the Y table 2 of the lower stage 20. In addition, in Example 1, the tilt of the upper stage 10 can be calculated with a simple configuration by attaching a linear scale 25 to the vertical surface 24 and attaching a sensor 15 that reads the linear scale 25 to the vertical surface 14.

In addition, in Example 1, the forward piping 32 is arranged along the Y-axis direction, makes a U-turn, and then is arranged along the Y-axis direction. Then, by displacing the U-turn point as the Y-table 2 moves in the Y-axis direction, it becomes possible to supply refrigerant to the Y-table 2 even if the lower stage 20 moves. Similarly, by arranging the forward piping 32 along the X-axis direction, makes a U-turn, and then is arranged along the X-axis direction, it becomes possible to supply refrigerant to the X-table 1 even if the upper stage 10 moves, by displacing the U-turn point as the X-table 1 moves in the X-axis direction.

In addition, in Example 1, the forward pipe 32 and the crossover pipe 33 are connected to the surface 16 perpendicular to the Y-axis direction of the X-table 1, and the crossover pipe 33 and the return pipe 34 are connected to the surface 28 perpendicular to the Y-axis direction of the Y-table 2. In this way, the pipes can be connected to the vertical surfaces on the same side of the X-table 1 and the Y-table 2, making it easy to connect the pipes. Also, the connection surface of the pipes may be appropriately selected in consideration of preventing vibrations caused by the circulation of the cooling water.

In addition, in the first embodiment, a heat exchanger 17 made by bending a single pipe is provided inside the X table 1, and a heat exchanger 27 made by bending a single pipe is provided inside the Y table 2, so that the X table 1 and the Y table 2 can be cooled efficiently.

In the first embodiment, the lower stage 20 is a guide rail type, but it may be a floating type stage. When the lower stage 20 is a floating type stage, the movement is not restricted by the guide rail 5, so there is no associated thermal deformation. However, when constructing the stage device 100, thermal deformation may occur due to the mixture of parts made of various materials. When materials with different linear expansion coefficients are connected, a curve occurs in which the part that expands more with an increase in temperature is on the outside of the radius of curvature, and the part that expands less is on the inside of the radius of curvature. Therefore, even if the lower stage 20 is a floating type stage, the X table 1 can be accurately leveled by suppressing the thermal expansion of the Y table 2, which is used as a reference.

In the first embodiment, the cooling water pipe 30 is configured in one stroke to cool both the X table 1 and the Y table 2, but the cooling water pipe 30 may be branched to cool each of the X table 1 and the Y table 2. The cooling water that has branched and cooled each table is returned to the junction pipe. Flow vibrations are likely to occur at the point where the pipes join. The configuration of the cooling water pipe 30 in one stroke in the first embodiment has the effect of preventing vibrations caused by the flow of cooling water. When the pipes vibrate, the vibrations are transmitted to the upper stage 10 and the lower stage 20, but preventing vibrations by eliminating the junction pipe leads to preventing vibrations of the X table 1 and the Y table 2.

It is also possible to provide independent cooling water piping 30 for each of the upper stage 10 and the lower stage 20. However, the upper stage 10 moves in the X-axis direction and also moves in the Y-axis direction following the lower stage 20. For this reason, the cooling water piping 30 of the upper stage 10 requires a U-shaped turn to follow the movement of the lower stage 20, and a U-shaped turn to follow the movement of the upper stage 10. In addition, since the lower stage 20 moves in the Y-axis direction, the cooling water piping 30 of the lower stage 20 requires a U-shaped turn to follow the lower stage 20. In other words, if independent cooling water piping 30 is provided for each of the upper stage 10 and the lower stage 20, overlapping cooling water piping 30 is required. For this reason, a single-stroke cooling water piping 30 has the effect of reducing the amount of piping.

In the uniaxial cooling water piping 30, when cooling one of the X-table 1 and the Y-table 2 with cooling water, the temperature of the cooling water rises by the amount of heat received, and the cooling effect of the other table is reduced. Therefore, in the uniaxial cooling water piping 30, the cooling effect of the table to which cooling water is supplied first is greater. In the first embodiment, the X-table 1 can be effectively cooled by supplying cooling water to the upper stage 10 first.

Example 2
FIG. 4 is a cross-sectional view of the stage device of the second embodiment. FIG. 4 is a cross-sectional view of the stage device 100 of the second embodiment cut along a plane perpendicular to the X-axis. The same components as those of the first embodiment are given the same reference numerals, and the description thereof will be omitted. In the second embodiment, as a component for cooling the Y table 2, instead of embedding the heat exchanger 27 inside the Y table 2, an external heat sink 128 is attached to the lower stage 20. The heat sink 128 has a flow path 129 for flowing a coolant therein. The heat sink 128 of the second embodiment may be a heat sink that does not flow a coolant, and may have a plurality of fins to increase the surface area.

Stainless steel piping may be embedded inside the heat sink 128 to serve as the flow path 129, or grooves may be machined into the base material of the heat sink 128 and a lid may be placed on it to form the flow path 129.

In FIG. 4, the configuration of the upper stage 10 is described in more detail than in Example 1. The upper stage 10 has an X table 1, the X mirror 3 (see FIG. 1) and Y mirror 4 described in Example 1, a top table 6, a chuck 7, and a coil 8.

The coil 8 of the Z motor is attached to the X table 1. The yoke 9 that pairs with the Z motor is installed on the Y table 2. The Z motor applies a force (= levitation force) in the Z direction to the upper stage 10, and includes a coil 8 that passes an electric current and a yoke 9 made of a magnetic material. Since the Z motor requires a small range of motion, the yoke 9 is made of a permanent magnet or a magnetic material such as non-magnetic iron. When a permanent magnet is used, an attractive force and a repulsive force can be generated between the coil 8 and the yoke 9 of the magnet. However, when a non-magnetic magnetic yoke 9 is used, only an attractive force is generated. For this reason, when a non-magnetic magnetic yoke 9 is used, the yoke 9 is placed on the upper side and the coil 8 is placed on the lower side. As a result, the coil 8 is levitated to a desired height by controlling the balance between the downward force due to gravity applied to the coil 8 and the upward force due to the magnetic attractive force.

The coils 8 are arranged at the four corners of the X-table 1. The four coils 8 are independently controlled by the control device 50. The control device 50 controls the levitation amount, pitching angle, and rolling angle of the upper stage 10. Since the upper stage 10 moves significantly in the X-axis direction, the stationary yoke 9 must be able to generate the same electromagnetic force in any position relative to the moving coil 8. If the yoke 9 is made of only a magnetic material and has a shape that extends in the depth direction of the paper in FIG. 4, the relationship between the coils 8 and the yoke 9 can be the same even if the upper stage 10 moves in the X-axis direction. Therefore, there are four coils 8, but there are two yokes 9. In other words, two coils 8 correspond to one yoke 9. The X-table 1 is equipped with a linear motor that applies thrust in the X-axis direction and a mechanism for following the movement of the lower stage 20 in the Y-axis direction, but these configurations are omitted in FIG. 4.

In the second embodiment, the X mirror 3, the Y mirror 4, and the chuck 7 are placed on the top table 6. The chuck 7 is for mounting a sample 80 such as a semiconductor wafer. Since it is difficult to directly measure the position of the sample 80 when positioning the sample 80, the positions of the reflecting surfaces of the X mirror 3 and the Y mirror 4 are measured to measure the XY coordinates of the sample 80. For this reason, it is important to prevent the positional relationship between the X mirror 3 and the Y mirror 4 and the sample 80 from changing. For this reason, the chuck 7 is made of a material that is resistant to thermal deformation, and the X mirror 3 and the Y mirror 4 are placed on the top table 6. The top table 6 is integral with the X table 1, but by connecting them with a pillar between them, the effect of deformation of the X table 1 on the position and angle of the X mirror 3 and the Y mirror 4 is reduced. The configuration of the upper stage 10 in the second embodiment can also be applied to the upper stage 10 in the first embodiment.

(Effects of Example 2)
Since various parts, such as a mechanism for moving the lower stage 20 in the Y-axis direction, are attached to the Y table 2, the lower stage 20 has a complex shape. By providing a heat sink 128 that is separate from the lower stage 20 having this complex shape, it is possible to prevent the lower stage 20 from becoming complicated. In addition, the manufacture of the lower stage 20 becomes easier, and the manufacturing precision of the lower stage 20 is improved.

Other effects are the same as in Example 1, so their explanation will be omitted.

Example 3
5 is a configuration diagram of a charged particle beam device in Example 3. The charged particle beam device 200 includes a stage device 100 therein. The stage device 100 inside the charged particle beam device 200 is the stage device 100 described in Example 1 or Example 2. The charged particle beam device 200 includes an electron microscope that applies an electron beam to a sample 80 such as a semiconductor wafer to be observed, to enlarge an image. The electron microscope includes an electron optical system barrel 90, a stage device 100, a sample chamber 40, and a distance measurement device 70.

The electron optical system column 90 has a charged particle source, and the beam emitted from the charged particle source is irradiated onto the sample 80. When the beam (electron beam) is irradiated onto the sample 80, the sample 80 is placed in a vacuum environment to avoid scattering by gas molecules. For this reason, the sample chamber 40 functions as a vacuum chamber. Although the cooling water pipe 30 is not shown in FIG. 5, the cooling water pipe 30 shown in FIG. 1 is installed in the sample chamber 40. The stage device 100 moves the chuck 7 carrying the sample 80 in the X-axis direction and the Y-axis direction. Since FIG. 5 is a cross-sectional view cut along a plane perpendicular to the X-axis direction, the cross section of the Y mirror 4 is shown. The Y mirror 4 has a reflective surface on the right side of the figure, and the distance measurement device 70 irradiates the reflective surface with laser light 71 to measure the Y coordinate of the Y mirror 4. This distance measurement device 70 is a laser interferometer type distance measurement device. This distance measurement device 70 is fixed to the sample chamber 40. Although not shown in FIG. 5, an X mirror 3 and a distance measurement device 70 that irradiates the reflecting surface of the X mirror 3 with laser light and measures the X coordinate of the X mirror 3 are provided at a position rotated 90°. Based on the Y coordinate of the Y mirror 4 and the X coordinate of the X mirror 3, the XY coordinates of the sample 80 placed on the stage device 100 are calculated.

The electron optical system barrel 90 is fixed to the sample chamber 40. Observing a sample with an electron microscope requires high magnification, so the distance between the electron microscope and the sample 80 cannot be large. For this reason, the distance between the electron optical system barrel 90 and the sample 80 is small. On the other hand, the X mirror 3 and the Y mirror 4 on the upper stage 10 may come directly below the electron optical system barrel 90 as the upper stage 10 moves. In order to prevent contact between the electron optical system barrel 90 and the X mirror 3 and the Y mirror 4, the tops of the X mirror 3 and the Y mirror 4 must be lower than the bottom of the electron optical system barrel 90. For this reason, the tops of the X mirror 3 and the Y mirror 4 cannot be significantly higher than the top surface of the sample 80. The reflecting surfaces of the X mirror 3 and the Y mirror 4 cannot be used up to the top of their vertical surfaces, and the verticality is guaranteed only up to a point a little away from the ridge that becomes the corner. For this reason, the laser light 71 irradiated by the laser interferometer type distance measuring device 70 must be lower than the top surface of the sample 80. As a result, the height of the XY coordinate plane where the position of the upper stage 10 is measured (the height of the laser light 71) is lower than the top surface of the sample 80. What the stage device 100 wants to position is the position on the top surface of the sample 80 where the electron beam is irradiated, and this is the XY coordinate on the top surface of the sample 80.

One of the principles of distance measurement is Abbe's principle, which states that errors are larger when distance measurement is performed on a parallel line compared to when distance measurement is performed on an extension line of two points on the measurement target. Measuring the XY coordinates of the upper stage 10 on a plane that is offset in height from the top surface of the sample 80 is similar to the conditions under which errors are large as indicated by Abbe's principle. The cause of the increase in error as indicated by Abbe's principle is explained as the axis of the measurement target and the point actually being measured are not perfectly parallel. Therefore, as the two approach perfect parallelism, the measurement error also decreases. Using this principle, it is believed that the positioning accuracy of the sample can be improved if the upper stage 10 can be brought closer to perfect horizontality.

To keep the levitating upper stage 10 horizontal, it is necessary to grasp the tilt angle of the upper stage 10 and control the upper stage 10 so that it is horizontal based on that tilt angle. Z motors (coils 8) installed at the four corners of the upper stage 10 can be used as actuators for control. For measuring the tilt angle of the upper stage 10, the method used in the explanation of Example 1 can be used to perform simple and accurate measurement. As a result, if the measurement accuracy of the tilt angle of the upper stage 10 is improved, the control accuracy for keeping the upper stage 10 horizontal increases, and the positioning accuracy of the sample improves.

(Effects of Example 3)
The effects of the charged particle beam device 200 of the third embodiment are similar to those of the first embodiment, and therefore the description thereof will be omitted.

The present invention is not limited to the above-mentioned examples, but includes various modified examples. The above-mentioned examples have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of one example with the configuration of another example, and it is also possible to add the configuration of another example to the configuration of one example. It is also possible to add, delete, or replace part of the configuration of each example with other configurations.

In the first embodiment, both X table 1 and Y table 2 are cooled, but only Y table 2 may be cooled. Also, in the first embodiment, X table 1 and Y table 2 are cooled in that order, but Y table 2 and X table 1 may be cooled in that order.

The levitating upper stage 10 in Examples 1 to 3 may be a type having an electromagnet that provides buoyancy to the upper stage 10 and a linear motor that provides thrust in one axial direction, or a type having a shaft motor that performs both levitation and propulsion functions in one.

The upper stage 10 in the first to third embodiments is a magnetic levitation type that levitates using electromagnetic force, but it may be an air bearing type that levitates using gas pressure.

1: X table 2: Y table 3: X mirror 4: Y mirror 5: Guide rail 6: Top table 7: Chuck 8: Coil 9: Yoke 10: Upper stage 11: Support 12: Joint 13: Joint 14: Vertical surface 15: Sensor 17: Heat exchanger 20: Lower stage 21: Support 22: Joint 23: Joint 24: Vertical surface 25: Linear scale 26: Slide unit 27: Heat exchanger 30: Cooling water pipe 31: Joint 32: Forward pipe 33: Crossover pipe 34: Return pipe 35: Joint 40: Sample chamber 50: Control device 51: Processor 52: Communication I/F 53: Main memory device 54: Auxiliary memory device 55: Input/output I/F 56: Bus 60: Stage drive mechanism 70: Distance measurement device 80: Sample 90: Electron optical system barrel 100: Stage device 128: Heat sink 129: Flow path 200: Charged particle beam device

Claims (14)

a first stage moving in a first direction;
a second stage that floats above the first stage and moves in at least a second direction perpendicular to the first direction;
a first cooling unit that cools the table of the first stage by a refrigerant;
a control device that controls a tilt of the second stage based on the table of the first stage cooled by the first cooling unit. A second cooling unit that cools the table of the second stage by a refrigerant is further provided,
2. The stage device of claim 1, wherein the refrigerant used to cool one of the first stage table and the second stage table is also used to cool the other of the first stage table and the second stage table. The stage device according to claim 2, characterized in that the refrigerant is used to cool the table of the second stage and then used to cool the table of the first stage. a first refrigerant pipe that supplies the refrigerant to the second cooling section;
4. The stage device according to claim 3, further comprising: a second coolant pipe that supplies the coolant supplied to the second cooling section from the second cooling section to the first cooling section. The stage device according to claim 1, characterized in that the second stage is levitated by a magnetic force between the second stage and the first stage. The stage device according to claim 1, characterized in that the first stage moves in the first direction on a guide rail arranged along the first direction. The stage device according to claim 1, characterized in that the control device measures the position of the second stage at multiple points based on a vertical plane provided on the table of the first stage, and controls the tilt of the second stage based on the measurement results. a linear scale attached to one of the vertical surface of the first stage and an opposing surface of the second stage facing the vertical surface;
a sensor attached to the other of the vertical surface and the opposing surface and configured to read the linear scale;
8. The stage apparatus according to claim 7, wherein the control device controls the tilt of the second stage based on the measurement result of the sensor. a mirror bar disposed on the table of the second stage;
measuring a position coordinate of the second stage based on the laser light reflected by the mirror bar;
2. The stage apparatus according to claim 1, wherein the control device controls the position of the first stage or the second stage based on the position coordinates. a refrigerant pipe that supplies the refrigerant to the first cooling section,
2. The stage device according to claim 1, wherein the refrigerant piping is arranged along the first direction, makes a U-turn, and then is arranged along the first direction, and the U-turn point is displaced as the first stage moves in the first direction. a refrigerant pipe that supplies the refrigerant to the first cooling section,
2. The stage device according to claim 1, wherein the coolant pipe is connected to a surface of the first stage that is perpendicular to the first direction. The stage device according to claim 1, characterized in that the first cooling unit is built into the table of the first stage and includes a single pipe having an inlet and outlet for the refrigerant. The stage device according to claim 1, characterized in that the first cooling unit includes a heat sink attached to a table of the first stage and having a flow path for the coolant. a charged particle source; and
a chuck for mounting a sample on which a beam emitted from the charged particle source is irradiated;
A stage device according to any one of claims 1 to 13, which moves the chuck;
and a vacuum chamber in which the stage device is installed.

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